/*
 * Copyright (c) Ian F. Darwin 1986-1995.
 * Software written by Ian F. Darwin and others;
 * maintained 1995-present by Christos Zoulas and others.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice immediately at the beginning of the file, without modification,
 *    this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
/*
 * compress routines:
 *  zmagic() - returns 0 if not recognized, uncompresses and prints
 *       information if recognized
 *  uncompress(method, old, n, newch) - uncompress old into new,
 *              using method, return sizeof new
 */
#include "config.h"
#include "file.h"

#ifndef lint
FILE_RCSID("@(#)$File: compress.c,v 1.70 2012/11/07 17:54:48 christos Exp $")
#endif

#include "magic.h"
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#ifndef PHP_WIN32
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif
#if defined(HAVE_SYS_TIME_H)
#include <sys/time.h>
#endif
#if defined(HAVE_ZLIB_H) && defined(HAVE_LIBZ)
#define BUILTIN_DECOMPRESS
#include <zlib.h>
#endif

#undef FIONREAD


#define NODATA ((size_t)~0)

private ssize_t swrite(int, const void *, size_t);
#ifdef PHP_FILEINFO_UNCOMPRESS
private size_t uncompressbuf(struct magic_set *, int, size_t,
    const unsigned char *, unsigned char **, size_t);
#ifdef BUILTIN_DECOMPRESS
private size_t uncompressgzipped(struct magic_set *, const unsigned char *,
    unsigned char **, size_t);
#endif

protected int
file_zmagic(struct magic_set *ms, int fd, const char *name,
    const unsigned char *buf, size_t nbytes)
{
  unsigned char *newbuf = NULL;
  size_t i, nsz;
  int rv = 0;
  int mime = ms->flags & MAGIC_MIME;
  size_t ncompr;

  if ((ms->flags & MAGIC_COMPRESS) == 0)
    return 0;

  ncompr = sizeof(compr) / sizeof(compr[0]);

  for (i = 0; i < ncompr; i++) {
    if (nbytes < compr[i].maglen)
      continue;
    if (memcmp(buf, compr[i].magic, compr[i].maglen) == 0 &&
        (nsz = uncompressbuf(ms, fd, i, buf, &newbuf,
        nbytes)) != NODATA) {
      ms->flags &= ~MAGIC_COMPRESS;
      rv = -1;
      if (file_buffer(ms, -1, name, newbuf, nsz) == -1)
        goto error;

      if (mime == MAGIC_MIME || mime == 0) {
        if (file_printf(ms, mime ?
            " compressed-encoding=" : " (") == -1)
          goto error;
      }

      if ((mime == 0 || mime & MAGIC_MIME_ENCODING) &&
          file_buffer(ms, -1, NULL, buf, nbytes) == -1)
        goto error;

      if (!mime && file_printf(ms, ")") == -1)
        goto error;
      rv = 1;
      break;
    }
  }
error:
  if (newbuf)
    efree(newbuf);
  ms->flags |= MAGIC_COMPRESS;
  return rv;
}
#endif
/*
 * `safe' write for sockets and pipes.
 */
private ssize_t
swrite(int fd, const void *buf, size_t n)
{
  ssize_t rv;
  size_t rn = n;

  do
    switch (rv = write(fd, buf, n)) {
    case -1:
      if (errno == EINTR)
        continue;
      return -1;
    default:
      n -= rv;
      buf = CAST(const char *, buf) + rv;
      break;
    }
  while (n > 0);
  return rn;
}


/*
 * `safe' read for sockets and pipes.
 */
protected ssize_t
sread(int fd, void *buf, size_t n, int canbepipe)
{
  ssize_t rv;
#ifdef FIONREAD
  int t = 0;
#endif
  size_t rn = n;

  if (fd == STDIN_FILENO)
    goto nocheck;

#ifdef FIONREAD
  if (canbepipe && (ioctl(fd, FIONREAD, &t) == -1 || t == 0)) {
#ifdef FD_ZERO
    ssize_t cnt;
    for (cnt = 0;; cnt++) {
      fd_set check;
      struct timeval tout = {0, 100 * 1000};
      int selrv;

      FD_ZERO(&check);
      FD_SET(fd, &check);

      /*
       * Avoid soft deadlock: do not read if there
       * is nothing to read from sockets and pipes.
       */
      selrv = select(fd + 1, &check, NULL, NULL, &tout);
      if (selrv == -1) {
        if (errno == EINTR || errno == EAGAIN)
          continue;
      } else if (selrv == 0 && cnt >= 5) {
        return 0;
      } else
        break;
    }
#endif
    (void)ioctl(fd, FIONREAD, &t);
  }

  if (t > 0 && (size_t)t < n) {
    n = t;
    rn = n;
  }
#endif

nocheck:
  do
    switch ((rv = FINFO_READ_FUNC(fd, buf, n))) {
    case -1:
      if (errno == EINTR)
        continue;
      return -1;
    case 0:
      return rn - n;
    default:
      n -= rv;
      buf = ((char *)buf) + rv;
      break;
    }
  while (n > 0);
  return rn;
}

protected int
file_pipe2file(struct magic_set *ms, int fd, const void *startbuf,
    size_t nbytes)
{
  char buf[4096];
  ssize_t r;
  int tfd;

  (void)strlcpy(buf, "/tmp/file.XXXXXX", sizeof buf);
#ifndef HAVE_MKSTEMP
  {
    char *ptr = mktemp(buf);
    tfd = open(ptr, O_RDWR|O_TRUNC|O_EXCL|O_CREAT, 0600);
    r = errno;
    (void)unlink(ptr);
    errno = r;
  }
#else
  {
    int te;
    tfd = mkstemp(buf);
    te = errno;
    (void)unlink(buf);
    errno = te;
  }
#endif
  if (tfd == -1) {
    file_error(ms, errno,
        "cannot create temporary file for pipe copy");
    return -1;
  }

  if (swrite(tfd, startbuf, nbytes) != (ssize_t)nbytes)
    r = 1;
  else {
    while ((r = sread(fd, buf, sizeof(buf), 1)) > 0)
      if (swrite(tfd, buf, (size_t)r) != r)
        break;
  }

  switch (r) {
  case -1:
    file_error(ms, errno, "error copying from pipe to temp file");
    return -1;
  case 0:
    break;
  default:
    file_error(ms, errno, "error while writing to temp file");
    return -1;
  }

  /*
   * We duplicate the file descriptor, because fclose on a
   * tmpfile will delete the file, but any open descriptors
   * can still access the phantom inode.
   */
  if ((fd = dup2(tfd, fd)) == -1) {
    file_error(ms, errno, "could not dup descriptor for temp file");
    return -1;
  }
  (void)close(tfd);
  if (FINFO_LSEEK_FUNC(fd, (off_t)0, SEEK_SET) == (off_t)-1) {
    file_badseek(ms);
    return -1;
  }
  return fd;
}

#ifdef PHP_FILEINFO_UNCOMPRESS
#ifdef BUILTIN_DECOMPRESS

#define FHCRC    (1 << 1)
#define FEXTRA    (1 << 2)
#define FNAME    (1 << 3)
#define FCOMMENT  (1 << 4)

private size_t
uncompressgzipped(struct magic_set *ms, const unsigned char *old,
    unsigned char **newch, size_t n)
{
  unsigned char flg = old[3];
  size_t data_start = 10;
  z_stream z;
  int rc;

  if (flg & FEXTRA) {
    if (data_start+1 >= n)
      return 0;
    data_start += 2 + old[data_start] + old[data_start + 1] * 256;
  }
  if (flg & FNAME) {
    while(data_start < n && old[data_start])
      data_start++;
    data_start++;
  }
  if (flg & FCOMMENT) {
    while(data_start < n && old[data_start])
      data_start++;
    data_start++;
  }
  if (flg & FHCRC)
    data_start += 2;

  if (data_start >= n)
    return 0;
  if ((*newch = CAST(unsigned char *, emalloc(HOWMANY + 1))) == NULL) {
    return 0;
  }

  /* XXX: const castaway, via strchr */
  z.next_in = (Bytef *)strchr((const char *)old + data_start,
      old[data_start]);
  z.avail_in = CAST(uint32_t, (n - data_start));
  z.next_out = *newch;
  z.avail_out = HOWMANY;
  z.zalloc = Z_NULL;
  z.zfree = Z_NULL;
  z.opaque = Z_NULL;

  /* LINTED bug in header macro */
  rc = inflateInit2(&z, -15);
  if (rc != Z_OK) {
    file_error(ms, 0, "zlib: %s", z.msg);
    return 0;
  }

  rc = inflate(&z, Z_SYNC_FLUSH);
  if (rc != Z_OK && rc != Z_STREAM_END) {
    file_error(ms, 0, "zlib: %s", z.msg);
    return 0;
  }

  n = (size_t)z.total_out;
  (void)inflateEnd(&z);

  /* let's keep the nul-terminate tradition */
  (*newch)[n] = '\0';

  return n;
}
#endif

private size_t
uncompressbuf(struct magic_set *ms, int fd, size_t method,
    const unsigned char *old, unsigned char **newch, size_t n)
{
  int fdin[2], fdout[2];
  ssize_t r;
  pid_t pid;

#ifdef BUILTIN_DECOMPRESS
        /* FIXME: This doesn't cope with bzip2 */
  if (method == 2)
    return uncompressgzipped(ms, old, newch, n);
#endif
  (void)fflush(stdout);
  (void)fflush(stderr);

  if ((fd != -1 && pipe(fdin) == -1) || pipe(fdout) == -1) {
    file_error(ms, errno, "cannot create pipe");
    return NODATA;
  }
  switch (pid = fork()) {
  case 0:  /* child */
    (void) close(0);
    if (fd != -1) {
        (void) dup(fd);
        (void) FINFO_LSEEK_FUNC(0, (off_t)0, SEEK_SET);
    } else {
        (void) dup(fdin[0]);
        (void) close(fdin[0]);
        (void) close(fdin[1]);
    }

    (void) close(1);
    (void) dup(fdout[1]);
    (void) close(fdout[0]);
    (void) close(fdout[1]);
#ifndef DEBUG
    if (compr[method].silent)
      (void)close(2);
#endif

    (void)execvp(compr[method].argv[0],
        (char *const *)(intptr_t)compr[method].argv);
#ifdef DEBUG
    (void)fprintf(stderr, "exec `%s' failed (%s)\n",
        compr[method].argv[0], strerror(errno));
#endif
    exit(1);
    /*NOTREACHED*/
  case -1:
    file_error(ms, errno, "could not fork");
    return NODATA;

  default: /* parent */
    (void) close(fdout[1]);
    if (fd == -1) {
      (void) close(fdin[0]);
      /*
       * fork again, to avoid blocking because both
       * pipes filled
       */
      switch (fork()) {
      case 0: /* child */
        (void)close(fdout[0]);
        if (swrite(fdin[1], old, n) != (ssize_t)n) {
#ifdef DEBUG
          (void)fprintf(stderr,
              "Write failed (%s)\n",
              strerror(errno));
#endif
          exit(1);
        }
        exit(0);
        /*NOTREACHED*/

      case -1:
#ifdef DEBUG
        (void)fprintf(stderr, "Fork failed (%s)\n",
            strerror(errno));
#endif
        exit(1);
        /*NOTREACHED*/

      default:  /* parent */
        break;
      }
      (void) close(fdin[1]);
      fdin[1] = -1;
    }

    *newch = (unsigned char *) emalloc(HOWMANY + 1);

    if ((r = sread(fdout[0], *newch, HOWMANY, 0)) <= 0) {
#ifdef DEBUG
      (void)fprintf(stderr, "Read failed (%s)\n",
          strerror(errno));
#endif
      efree(*newch);
      n = 0;
      newch[0] = '\0';
      goto err;
    } else {
      n = r;
    }
     /* NUL terminate, as every buffer is handled here. */
     (*newch)[n] = '\0';
err:
    if (fdin[1] != -1)
      (void) close(fdin[1]);
    (void) close(fdout[0]);
#ifdef WNOHANG
    while (waitpid(pid, NULL, WNOHANG) != -1)
      continue;
#else
    (void)wait(NULL);
#endif
    (void) close(fdin[0]);

    return n;
  }
}
#endif /* if PHP_FILEINFO_UNCOMPRESS */
